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Employee Benefit Plan - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
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Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
United States [Member] |  |  |
Schedule Of Pension And Other Postretirement Benefits Expected Benefit Payments [Line Items] |  |  |
Contribution pension plan | $ 116 | $ 111 | $ 100
Belgium [Member] |  |  |
Schedule Of Pension And Other Postretirement Benefits Expected Benefit Payments [Line Items] |  |  |
Contribution pension plan | $ 655 | $ 542 | $ 515

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- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Details
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Namespace Prefix: | vdsi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration